This invention generally relates to Pipe Interior Surface Coating Devices and, more specifically, to airless type spray devices used in painting the interior surface of a pipe.
In U.S. Pat. No. 3,915,382, I described an airless type extension spray gun enabling a painter to reach high overhead locations without the use of ladders. This extension spray gun apparatus basically comprises a pole, which is telescopically extendable having a locking device to lock it at any length desired, a spray nozzle pivotally connected to one end of the pole, and a valve located at the other end of the pole with the flexible hose extending between the valve and spray nozzle. I have since determined that this type spray gun might be used beneficially in painting the interior surface of pipes. However, because of the uneven spray and back pressures which occur when spraying in a closed location, I have found that this apparatus is difficult to use in spraying the interior surface of a pipe.
I then developed apparatus comprising a pole, which is telescopically extendable. A spray head having opposed nozzles is rotatably secured to one end of the pole and a valve is located at the other end of the pole. A flexible hose extends through the pole between the valve and the spray head to supply a coating material to the head. Self centering telescoping guide arms are used to position the axis of rotation of the spray head nozzle along the longitudinal axis of the pipe such that the two axes coincide to assure an even distribution of coating material or paint on the interior surface of the pipe. This device is described in an article entitled "Taking the `Pain` Out of Painting", Engineering Notes. by Mr. Theodore Dowd, Ocean Engineering Division, U.S. Coast Guard Headquarters, Winter, 1978.
A number of other devices for coating the interior surface of a pipe are described in U.S. Pat. Nos. 2,520,397; 3,606,862; 3,960,644; and 3,987,963; and in British Patent Specification No. 400,363. However, none of these pipe interior surface coating devices provide an even distribution of coating material to the interior surface as desirable because none of the devices have a rotating spray head with connecting apparatus to adjustably connect spray tips to whirler tubes for varying the angle of each spray tip relative to a radial line extending from the axis of rotation so that the rotational speed of the spray tips may be adjusted. Further, no prior art device provides even distribution because the devices do not employ a rotating spray head supported by apparatus permitting a longitudinal displacement of the spray head from the supporting apparatus. Further, devices heretofore developed could not provide even distribution of the paint in pipes of different diameters because the supporting apparatus was not adjustable to maintain the axis of rotation of the spray head aligned with the axis of the pipe and then fixed in such adjusted position.
Accordingly, it is an object of the present invention to provide a pipe interior surface coating device that supplies an even distribution of coating material to a pipe section by using apparatus which permits positioning of the rotating spray head a chosen distance outwardly or longitudinally of the support apparatus carrying the spray head through the pipe section being coated.
Further, it is an object of the present invention to provide a pipe interior surface coating device that supplies an even distribution of coating material to the interior surface of a pipe by varying the rotating speed of the rotating spray head.
In accordance with the invention, a pipe interior surface coating device, comprises a spray apparatus for distributing a coating material around an axis of rotation. A carriage supports the rotating spray apparatus for movement longitudinally through a pipe section. The carriage includes a frame with first and second ends and first and second sets of rollers for supporting each end of the frame. A leg is pivotally connected to each roller and a sleeve for receiving each leg is connected to the frame. A screw is threadedly connected to each sleeve for urging the leg received therein into engagement with a side of the sleeve. The rollers are thus moved radially of the axis of rotation when the leg is not engaging the sleeve to thereby position the axis of rotation of the spray apparatus concentrically within the pipe and then fixed in position by engagement of the leg with the sleeve.
Further, in accordance with the invention, a pipe interior surface coating device comprises a carriage adapted to be moved longitudinally inside a pipe section having first and second ends. A bracket is supported by the carriage and has a first and second end. A rotating spray apparatus is connected to the second end of the bracket for distributing a coating material around an axis of rotation. Apparatus is used to connect the bracket to the carriage when the rotating spray apparatus is disposed a chosen distance longitudinally of the second end of the carriage.
Further, in accordance with the invention, a pipe interior surface coating device, comprises a carriage adapted to be moved longitudinally inside a pipe. A spray apparatus is supported by the carriage for distributing a coating material around an axis of rotation. The rotating spray apparatus includes a swivel, a set of whirler tubes disposed to receive coating material and connected to the swivel for rotating around the axis of rotation of the spray apparatus, and a spray tip disposed in fluid communication with each whirler tube for directing a coating material toward the interior surface of the pipe. Apparatus is used to adjustably connect each spray tip to each whirler tube to vary the angle of the spray tip relative to a radial line extending from the axis of rotation so as to adjust the rotational speed of the spray tips around the axis of rotation.